Method of making variable reluctance position transducer



Dec. 16, 1969 w, w. MALCOLM ETAL 3,483,613

METHOD OF MAKING VARIABLE RELUCTANCE POSITION TRANSDUCER Filed April 8, 1966 25B L J 258 FIG. 3 25A FIG-I William W. Malcolm United States Patent 3,483,613 METHOD OF MAKING VARIABLE RELUCTANCE POSITION TRANSDUCER William W. Malcolm, Huntsville, Ala., and Richard L. Moore, Richardson, Tex., assignors to the United States of America as represented by the Secretary of the Army Filed Apr. 8, 1966, Ser. No. 541,395 Int. Cl. G01r 3/00; H01f 7/06 US. Cl. 29595 1 Claim ABSTRACT OF THE DISCLOSURE The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to a method of making an improved shaft angular position variable reluctance pickup transducer. A linear analog voltage with respect to shaft angle is obtained over a greater angle than with prior art devices, and a more compact device is obtained than the prior art devices, for a given output.

Heretofore, it has been difficult to obtain a linear voltage output from a transducer responding to an angular shaft position except over a small angle. Typical, known microsyns are only linear over relatively small angles, such as i from a median shaft position, while the invention is linear over Moreover, the instant device obtains th'is linearity with a reduction in size of the device, because of the method by which the device is made.

An object is to provide a method whereby an improved shaft-angle to voltage transducer may be fabricated.

Another object is to provide a shaft angle to voltage transducer which is simple in construction and which permits relatively wide manufacturing tolerences.

Briefly, the invention is a method of assembly a transducer, which transducer is a four pole of magnetic material having a primary and a secondary winding on each pole and with an armature of magnetic material carried by a shaft rotatable to vary the coupling between the primary and secondary windings on each pole.

The stator consists of a plurality of laminations, each lamination comprising a quarter section of the overall outline of the stator. These laminations each have a pole section and an annular section on one side of the pole section. The pole sections are inserted into stator windings with alternate laminations having their annular sections oppositely disposed to each other. The windings plus laminations assemblies are then mated together by interleaving the annular sections of the laminations. Before the final assembly is mated, the armature is inserted amongst the other assemblies. The final assembly is then mated and the armature is surrounded by the stator.

The outermost laminations of the stator are made appreciably thicker than the remainder of the laminations in order to impart structural rigidity thereto.

The invention may be best understood by reference to the drawings, in which the same numerals are used for 3,483,613 Patented Dec. 16, 1969 the same elements in the diflferent figures and in which:

FIGURE 1 shows a physical embodiment of a transducer made in accordance with the invention, with a portion cut away.

FIGURE 2 is a sectional view in the direction of the section line 22 of FIGURE 1, and

FIGURE 3 shows the shape of one of the stator laminations.

Referring to FIGURE 1, the assembled stator 20 has four plates 21, 22, 23 and 24. The stator is composed of a plurality of layer of segmental laminations of the shape as shown in FIGURE 3. Coils A, B, C and D are respectively carried by poles 21, 22, 23 and 24. The rotor is seen to consist of a shaft 30 having two armatures 31 and 34 thereon of which armature 34 can be seen in FIGURE 1.

Referring to FIGURE 2, armature 31 includes two ninety degree sectors 32 and 33 and armature 34 has two ninety degree sectors 35 and 36. In use, shaft 30 is surrounded by poles 21, 22, 23 and 24 with armatures 31 and 34 on opposite sides of stator 20 and closely spaced from poles 21-24. The rotor is machined from a single piece of metal and is consequently of uniform magnetic properties throughout. Stator 20 consists of layers of segmental laminations, such as 25 and 25'. Each of the segments 25 and 25' have the shape as shown in FIGURE 3. The segments of any given layer are so positioned that the annular portion of one of the segments is abutted by the pole portion of another segment. This can be seen from the two layers visible in FIGURE 1. An examination of the left side of FIGURE 1 reveals that portions 25A and 25B of two of segments 25 abut. The cut-away lower portion of this figure reveals that portions 25A and 25B abut. The hidden lines showing underneath segments 25 reveal the joints at which segments 25 abut.

r The joints of alternate layers of stator 20 line up.

Assembly of stator Referring to FIGURE 3, each lamination consists of an annular portion 25A and a pole portion 25B. The pole portion 25B is inserted into a coil, such as B. Additional laminations are inserted until the coil is filled. Alternate laminations are inserted so that the portions 25A are oppositely disposed to each other. When the laminations for each coil have been inserted, the annular portions 25A of the laminations are interleaved, those laminations associated with coil B being interleaved with those of coils A and C, those of coil A being interleaved with those of coils B, D, etc. Before the final set of laminations are interleaved, rotor 31 is placed in position among the coils.

The advantages of this type of assembly are twofold. Firstly, this type of assembly allows larger coils to be used than if the stator laminations were not of the sectional type as shown, but were in the form of the assembled stator as shown. Secondly, the rotor can be much larger than would be possible if the rotor had to be inserted through the opening between the poles. It would obviously be possible to employ a rotor composed of several parts and press the parts together on either side of the poles, but the advantage of a single piece rotor would not be obtained. The making of the rotor of a single piece of metal avoids magnetic anomolies that might be present in a built up rotor, and insures accurate parts alignment. The use of large coils on the pole pieces allows a greater voltage output to be obtained than with a standard assembly. In practice, it is possible to use a smaller transducer than a prior art transducer, for a given output. The rotor of the invention also allows the transducer to have a linear output over a greater angular range than prior art transducers. The linear range of a typical prior art transducer is :15". Such a typical transducer is the microsyn signal generator produced by the Elipse-Pioneer Division of Bendix Corporation and designated HA6Al. The transducer of the invention has a linear range of 125.

We claim:

1. The method of assembling an electromagnetic device having a plural pole stator and a rotor, with at least one electrical winding for each pole of said stator, said stator comprising a plurality of segmental laminations, each lamination having a pole portion and an annular portion on one side of said pole portion, which method comprises the steps of:

forming said plurality of poles of said stator by inserting the pole portions of a plurality of laminations in each of said windings with alternate laminations having said annular portions oppositely disposed to each other, and

interleaving the annular portions of the laminations inserted in the different windings, and

inserting said rotor between said poles before the completion of the interleaving of the laminations,

References Cited UNITED STATES PATENTS 2,469,100 5/1949 Andrus 310-216 X 3,005,969 10/1961 Wysocki 336-134 3,267,400 8/1966 Craige 336134 2,634,388 4/1953 Harshbarger 3l8--437 X JOHN F. CAMPBELL, Primary Examiner US. Cl. X.R. 

